The overall objective of this proposal is to contribute to the understanding of the role of blood-born monocytes, a precursor of free and fixed macrophages, in the pathogenesis of human periodontal disease specifically and other chronic inflammatory lesions in general. This proposal presents protocols for the isolation of human peripheral blood monocytes in pure fractions prior to introduction into culture, and for the study of modulations in their phenotypic expression as a result of specific treatment. The initial emphasis is directed toward the isolation and introduction of human monocytes into culture under conditions which will retain these cells as structurally and functionally identical to their free circulating state in-vivo. The consequences of specific treatments with regard to the survival, proliferation, synthetic and secretory capacities will then be studied. Specifically the experiments will focus on the synthesis and secretion of hydrolytic enzymes, neutral proteases, bone resorbing factors and complement and in addition will relate these capacities with the survival of proliferation of mononuclear phagocytes (MP) in vitro. Data derived from these studies will provide information on the regulation of functional potentials of monocytes once they have escaped the blood stream. In addition this information may help to clarify cause and effect relationships between the presence of macrophages in inflamed tissues and subseqeunt connective tissue damage and may, therefore, lead to the identification and further characterization of factor(s) active in mediating the destruction of inflamed tissues.